Generally, a fuel cell system applied to a hydrogen fuel cell vehicle is configured to include a fuel cell stack that generates electrical energy from the electrochemical reaction of reaction gas, a hydrogen supply device that supplies hydrogen as a fuel to the fuel cell stack, an air supply device that supplies air containing oxygen as an oxidant required for the electrochemical reaction to the fuel cell stack, and a heat and water management system that releases heat as a byproduct of the electrochemical reaction in the fuel cell stack to the outside, optimally controlling an operating temperature of the fuel cell stack and performing water management functions.
In this configuration, the fuel cell stack generates electrical energy from the electrochemical reaction between hydrogen and oxygen as the reactive gasses, and discharges heat and water as the reaction by-product. Thus, the fuel cell system essentially requires an apparatus that cools the stack.
The heat and water management system includes a de-mineralizer, and the de-mineralizer serves to remove metal ions from the cooling water discharged after circulating through the fuel cell stack for the purposes of extending the life expectancy of the fuel cell and for stabilizing the fuel cell system.
The de-mineralizer of the fuel cell vehicle is located on the stack cooling water loop, and serves to ensure the electric stability of the system through ion-filtering so as to prevent electric shock.
For example, by mounting the ion resin inside the cartridge, the electric conductivity increased by cations/anions present in the stack cooling water are removed and managed to a certain criteria or less, to improve the insulation stability of the vehicle.
Particulate ion resin for substantially filtering ions contained in the cooling water is built in the interior of the de-mineralizer. The cooling water discharged after circulating through the fuel cell stack enters the de-mineralizer and, after the metal ions are removed by its internal ion resin, the cooling water circulates again to the fuel cell stack. Thus, the degree of ions in the stack cooling water, or its electric conductivity, can be appropriately controlled.
Various types of such ionic filters are disclosed in Korean Patent Publication No. 10-2006-0114700, Korean Patent Publication No. 10-2011-0061725, and Korean Patent Publication No. 10-2012-0016059.
FIG. 1 is a schematic diagram that shows a flow direction of the cooling water of the conventional de-mineralizer, FIG. 2a is a diagram that shows a cartridge assembly of the conventional de-mineralizer, and FIG. 2b is a diagram that shows an inner cartridge in the conventional cartridge assembly.
The conventional de-mineralizer is a part that filters the ions contained in the cooling water entering the fuel cell stack to lower the electrical conductivity of the cooling water to a certain level or below. As shown in FIG. 1, the conventional de-mineralizer is configured to include a housing 10 through which the cooling water normally passes, cooling water inlet 12 and outlet 14 through which the cooling water is introduced/discharged into the housing 10, an ion resin 16 that is filled in the housing 10 to filter the ions contained in the cooling water, and a cartridge assembly 20 that supports the ion resin 16 filled in the housing 10 and prevents leakage.
As shown in FIGS. 1 and 2a, the conventional de-mineralizer cartridge assembly 20 is configured to include an inner cartridge 22 disposed inside and an outer cartridge 26 disposed outside.
The inner cartridge 22 is formed by the following procedure. After a general mesh network is rolled in a cylindrical shape and two points of the rolled-mesh network are joined by spot welding, the welded mesh net is seated on the metal mold. Thereafter, the resin is injected at a high pressure, and a frame 24 is molded on the outside of the mesh network 23.
The mesh network 23 is a network formed by arranging wires extending in horizontal and vertical directions at uniform intervals. A burning phenomenon, in which a mesh network burns during spot welding due to being wound in a cylindrical shape, may occur, and the mesh network welding portion is then not joined due to the welding defect. Thus, a phenomenon in which the mesh network overturns and is pushed by the injection pressure during resin injection in the process of seating the mesh network in a metal mold and performing the injection molding of the frame occurs. This causes an injection failure of the frame, and the injection failure of the frame 24 leads to a leakage of ion resin in the filter.
When such leaked ionic resin flows along the cooling water flow path of the stack, the leaked ionic resin blocks a cooling water flow path within a stack separating plate. Thus, the cooling water does not flow and a burning of the stack separating plate occurs.
In addition, as shown in FIG. 2b, the frame 24 of the inner cartridge has a form in which a horizontal frame portion 24a formed outside of the mesh network 23 intersects with a vertical frame portion 24b. The horizontal frame portion 24a has a function of distributing the flow of cooling water, and the vertical frame portion 24b has a function of fixing the mesh network 23.
The horizontal frame portion 24a is arranged by forming a spacing in a pattern where the spacing gradually becomes wider as it goes to the outlet side from the cooling water inlet side, thereby evenly distributing the flow of the cooling water.
Typically, since the pressure of the cooling water inlet side is the highest in the de-mineralizer, the cooling water inlet side has the highest cooling water flow rate, and there is a difference in life expectancy of the ion resin of the inlet side and that of the outlet side. Even if the life expectancy of the output side of the ion resin remains, the filtering efficiency is rapidly lowered when the life expectancy of the inlet side of the ion resin decreases. Thus, in order to prevent such a phenomenon, a uniform distribution of the cooling water is induced through the spacing adjustment of the horizontal frame portion.
However, the conventional ion filter as described above needs to mold a plurality of horizontal frame portions when molding the frame by differentiating the spacing of the horizontal frame portions for the uniform distribution of the flow rate of the cooling water. This may cause an increase in differential pressure of the cooling water, a decline in filtering efficiency and a failure of efficient uniform distribution of the cooling water.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.